Depressurization strategy of automatic depressurization system for advanced pressurized water reactor

China’s advanced pressurized water reactor is simulated using a system analysis code. A strategy for operating the reactor’s automatic depressurization system (ADS) when it is inadvertently opened is investigated. Results show that under four typical ADS pipeline failure conditions, the ADS can effectively release the primary loop pressure and maintain the safety of reactor core. The redundancy of the two sets of independent ADS depressurization pipelines is designed to be 2 × 100%. The step-by-step opening of pipelines ADS-1–ADS-3 can effectively improve the depressurization and cooling rates of the primary loop. Pipeline ADS-2 is effective for accelerating depressurization, and pipeline ADS-3 can be regarded as the redundancy of ADS-2. The step-by-step opening of the pipelines increases the inlet pressure and widens the inlet pressure curve of the sprayer, enabling the sprayer to maintain a long and stable critical jet state.